On 01/19/21 16:52, Anthony PERARD via groups.io wrote: > On Tue, Jan 19, 2021 at 03:49:34PM +0100, Laszlo Ersek wrote: >> On 01/19/21 10:37, Julien Grall wrote: >>> Hi Igor, >>> >>> On 13/01/2021 03:42, Igor Druzhinin wrote: >>>> We faced a problem with passing through a PCI device with 64GB BAR to >>>> UEFI guest. The BAR is expectedly programmed into 64-bit PCI aperture at >>>> 64G address which pushes physical address space to 37 bits. That is above >>>> 36-bit width that OVMF exposes currently to a guest without tweaking >>>> PcdPciMmio64Size knob. >>>> >>>> The reverse calculation using this knob was inhereted from QEMU-KVM >>>> platform >>>> code where it serves the purpose of finding max accessible physical >>>> address without necessary trusting emulated CPUID physbits value (that >>>> could >>>> be different from host physbits). On Xen we expect to use CPUID policy >>>> to level the data correctly to prevent situations with guest physbits > >>>> host physbits e.g. across migrations. >>>> >>>> The next aspect raising concern - resource consumption for DXE IPL >>>> page tables >>>> and time required to map the whole address space in case of using CPUID >>>> bits directly. That could be mitigated by enabling support for 1G pages >>>> in DXE IPL configuration. 1G pages are available on most CPUs produced in >>>> the last 10 years and those without don't have many phys bits. >>>> >>>> Remove all the redundant code now (including PcdPciMmio64.. handling >>>> that's >>>> not used on Xen anyway) and grab physbits directly from CPUID that should >>>> be what baremetal UEFI systems do. >>>> >>>> Signed-off-by: Igor Druzhinin <igor.druzhi...@citrix.com> >>> >>> Reviewed-by: Julien Grall <jul...@xen.org> >> >> I'm going to hold this patch until Anthony responds in this thread as well: > > This new patch is fine, I didn't notice that it was a replacement for > the previous one. > > Reviewed-by: Anthony PERARD <anthony.per...@citrix.com>
[ler...@redhat.com: fix up authorship from groups.io-mangled From line] [ler...@redhat.com: wrap commit message at 74 characters] Merged via <https://github.com/tianocore/edk2/pull/1369>, as commit e68c2a22caae. Thanks Laszlo
